Our primary criterion for including a surge is that one or more users are interested in accessing data for that event. Since the aim of the project is to improve the uptake of satellite data we only look at events for which such data are available. In practice this means that we focus on events from 1991 onwards. We have also limited ourselves to specific areas of interest, although we are willing to add new areas if there is demand.

A surge could be "interesting" for several reasons. As well as the obvious case of a surge causing significant flooding, we also try to include examples of surges without flooding (e.g. a high surge at low tide), or where the surge was lower than predicted, where users may be interested in finding out why the models were wrong.

How are the data for each surge event (SEV) selected?

Each surge event is associated to an area of interest (AOI), i.e. a geographical region enclosing the data of interest. The event is also assigned a nominal date and a timebox around this nominal data, i.e. the period before/after the event during which data will be collected. This period is chosen so as to collect data showing the development and aftermath of the surge. We then find all data sets which fall (even partially) within this region and time period.

How have AOIs been chosen, and how is a surge event assigned to an area?

The AOI boundaries have been chosen such they they should enclose the region for which storms (leading to surges) develop, so that for a given surge an AOI will typically enclose all relevant data. This does mean that in some cases more data is gathered than strictly necessary, however the system allows the user to select only a relevent subset of this data for downloading.

In some cases AOIs overlap, or in extreme cases are nested (e.g. AOI-30 is within AOI-10). This is to allow the option of capturing data for a smaller area; e.g. for a surge within the Irish Sea data outside this region is not relevant. A given surge event is associated to the most appropriate AOI, e.g. to the smaller one if a local event, or the larger one if a wider event.

In some cases a storm may affect two different AOIs (this is particularly true for the North and Baltic seas); in such cases two different SEVs are created, each associated to a different AOI.

Why do some data appear to fall outside the Area of Interest for a given surge?

The procedure that we use for capturing data for a surge event (SEV) involves finding all data sets which lie - or partially lie - within the area of interest (AOI) that the SEV is associated with. In some cases this may mean that a given data set is associated with an event even though it mostly falls outside the AOI. We have chosen to include such data sets as they may nevertheless be of interest to some users.

The preview tool allows users to check whether any given data set is relevant before downloading it.

I am interested in a surge which is not in the database; can this be added to the database?

Yes. Initially the database includes around 50 events which our users have requested. We intend to gradually increase this to around 200 events. Ideally these should also be requested by users.

To request that a surge event be added, please contact us with details of this surge. We need to know the area affected, the nominal date of the surge, and the time before/after the event which is of interest. If your event falls outside our current areas of interest that is not a problem, we are willing to add others.

Please note that we are mainly interested in events after 1991, as before this date significant satellite data are not available.